We can apply the ideal gas law which tells us the following:
Where,
P is the pressure = 1atm (STP)
T is the temperature = 273.15K (STP)
R is the ideal gas constant = 0.08206 (atm L)/(mol K)
n is the number of moles
V is the volume in L
So, we have to calculate first the number of moles. We will use the molar mass of H2.
Molar mass of H2 = 2.01568 g/mol
Now, we replace the know values in ideal gas law:
So, 4374.4 grams of H2 gas are equal to 48644.0 L